I wear two hats in my world: I am both an investigative attorney and physical security/communications expert. For the past forty years, I have worked investigations, both criminal and civil, first for government agencies and then private corporate clients. These cases have mainly involved major insurance fraud, heists, technology related crimes, exploits of communications systems, and other offenses, some terrible and others more mundane. I also work for many of the major lock manufacturers in the world and run a team that figures out how to compromise these locks in seconds, then fix them. My story was pretty much summed up by Wired Magazine in a feature article in 2009, when I was dubbed the "Keymaster." I have always believed that full disclosure of security vulnerabilities in locks and related systems should be the rule, unless it involves national security, in order that the consumer, business sector and government understand potential risks. I solicit your input at mwtobias@security.org and your comments on my blog. My security website is www.security.org and my security blog is in.security.org

How to Switch Carriers With Your New iPhone 5s Or 5c

If you are using an AppleApple iPhone 5c or 5s you can easily switch your service among three of the four major carriers in the United States. In my article last week I explained how the new iPhones use a wider range of radio spectrum to operate on either Verizon, AT&TAT&T, or T-Mobile. You’re no longer locked into one specific carrier in North America. No longer will your investment in an expensive handset deter you from switching.

In order to make your phone work on a different carrier you need to understand some basics to make the process simple and straightforward. Hopefully this will answer the many questions that I have received since posting the article.

Here is what you need to do:

A valid and active SIM card: You must have a valid and active nano-sized SIM card and assigned phone number for the carrier. Be sure that a data plan is also activated for your phone on the new carrier. Remember that the SIM card must be set for an Apple smartphone; SIMs for tablets or Android phones will not work because they carry a different class identifier.

Depending upon your service provider there is a slight difference in procedures between AT&T, Verizon, and T-Mobile.

Verizon and AT&T: The carrier requires that the electronic serial number of the phone (IMEI) and the serial number (ICCID) of the SIM card be entered into their system to authenticate the phone. While the voice portion will work, data will not without this being accomplished.

T-Mobile: You can insert a SIM card from T-Mobile into a phone originally sold for any of the three carriers and it will work without any further registration. Just reboot the phone to register it.

You can physically replace the SIM card by inserting the tool that is supplied by Apple into the tiny hole on the right hand side of the phone. You can also use a small paper clip or even the end of a staple. When you depress and release the SIM tray, it will pop out slightly from the body of the phone. Just remove it and insert the new SIM. You will see that it is indexed to the correct position by an angled corner that mates with the SIM tray. It is inserted contact-side down, towards the back of the phone. Just slide the tray with the new card back into the slot.

Phone must be unlocked: This means there are no software restrictions that limit its use to one carrier. The status of your phone depends on where you purchased it; each of the four major cellular companies in the U.S. have slightly different locking policies when they sell you a handset.

From an Apple store: All models are locked with the exception of the generic GSM version which is designed to operate on virtually any GSM network. This model is identical (A1533) to the AT&T phone except that it is not designed specifically for any one carrier. If you purchase this version from Apple you can use it on AT&T or T-Mobile.

Verizon: All 4G devices, including the iPhone 5, 5s, and 5c are unlocked as a matter of corporate policy;

AT&T:This phone is locked when you purchase it from its stores. It can be unlocked by calling technical support at 800-331-0500 or by going to its web site.

T-Mobile: The phones are locked, but T-Mobile will unlock them after forty days from the date of purchase.

Sprint: Will not unlock their phones nor can they be registered on any other network.

The phone’s profile may need to be updated: There is a profile for each carrier that allows the connection to be made to their data network. This profile only appears when you insert a SIM card that is not issued by the carrier for which the phone was originally designed. The updating of the phone must be accomplished before you can access the Internet or any data. Note that you should have an active WiFi connection before you change the profile because you will lose connectivity once you erase the current settings.

T-Mobile: Insert their SIM card and the phone should work. In the event it does not, you can follow the procedure outlined for the other two carriers below. T-Mobile will automatically populate the APN settings on your phone.

For AT&T and Verizon, go to http://unlockit.co.nz for a complete list of carrier APN settings. This site will allow you to delete and update the settings for virtually all carriers in the world. Be sure you are able to access the site on WiFi before doing the update.

AT&T: You must first delete the current profile and then update it for the required settings for AT&T. With another carrier SIM card installed you can delete the APN profile by going to General, Profile, Remove APN carrier settings.

When you are on the unlockit website, select the country, carrier, and service. For AT&T, you must select the service (4G or LTE) that is used in the location where you are updating the phone. This means that if you are in a 4G area, the LTE profile will not work properly until you are in an area that supports LTE. In other words, the phone needs to be able to communicate with the network at its current location during the update. For AT&T, select the HSPA+ option if you are in a 4G area; otherwise select LTE.

Once you enter the country, carrier and service, the unlockit site will allow you to update the profile. It’s that simple. If there is a current profile that has not been deleted, the site will first display a ‘delete profile’ option to clear the old data. Do this, and then update the profile as described above. Then reboot the phone and it should display the new carrier and service.

Verizon: Follow the same procedure as for AT&T, except that the profile is Verizon LTE on the unlockit site.

Other Issues

If you have a Verizon 5s or 5c and you update it to AT&T, you can switch back and forth without having to reload the settings after the first update;

You cannot purchase an iPhone from the carriers unless you already have a service plan or are activating new service. If you set up service or upgrade on Verizon, you will receive an unlocked phone. You can then cancel, but you will pay full price;

If you buy a T-Mobile or AT&T phone you must have the carrier unlock it;

If you purchase a Verizon phone from Apple, it is locked, (as is the AT&T and T-Mobile version). However, once you log on to the Verizon network, it will unlock just as if you had purchased it directly from them. There is no difference between the phones you purchase from Apple and directly from the carriers in terms of programming or capabilities, other than being locked;

If you purchase the generic GSM version from an Apple store, the phone will work virtually anywhere in the world on GSM networks;

Any unlocked GSM-capable phone can be used on any network in the world with a local SIM card;

Finally, if you have an iPhone 4S or iPhone 5 you can have it unlocked and it will work with a local SIM card in most foreign countries.

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I currently have basic phone service with Verizon and am not on contract. Am planning to purchase new Iphone 5s at subsidized price W/2yr contract. Verizon and AT&T are my choices. However, I travel to Japan at least once per year. Need an unlocked phone to get local SIM while in Japan. The reason for my comment is that AT&T will NOT unlock your phone UNTIL after TWO YEARS. Going here https://www.att.com/deviceunlock/client/en_US/? I noticed one of the unlock requirement bullet points “The AT&T Mobile Device has been paid for in full.” I just got off the phone with customer service. What that means is that you either A)have to pay FULL RETAIL PRICE for the phone (not the subsidized contract price) or B)Wait until your TWO YEAR contract is complete. AT&T customer service rep said previoulsy they could utilize situational “waivers” (frequent travelers, etc.) but no longer. It is all done via the website application process and you WILL BE DENIED 100% unless the conditions I just stated above are met. That is too bad. I was really considering AT&T (I wanted the ability to surf & Talk simultaneously, impossible on Verizon I phone 5S), however, AT&T’s continuously LAME CUSTOMER NO-FRIENDLY service with regard to unlocking is a deal breaker for me. I will stick with Verizon. T-mobile (while free data/text and 0.20/min is attractive) is just too substandard a service for me. I can’t stand dropped calls. All my friends with T-mobile get dropped calls.

After a friend at work mentioned the iPhone 5s had all the radios required to switch network I eagerly began searching the internet or more information as I needed to accomplish this very task. I have an iPhone 5s that was acquired through At&t and I need to take it over to Verizon. This article was the one that stood out on my Google search so I set off to attempt the carrier switch. First I had my 5s factory unlocked through At&t with little to no trouble successfully then took my nano SIM from Verizon and popped it into my freshly unlocked iPhone. No service…searching….no service! Called Verizon and they said they couldn’t see the phone’s IMEI in their system (even in its unlocked state). More internet research ensued and I finally discover the above article is indeed incorrect. The At&t iPhone 5s does not possess the radios necessary to work voice calls on Verizon and cannot be altered in any way to do so. So although I appreciate the subject of the article I was greatly disappointed to find out the author did not research thoroughly and lead me on a wild goose hunt.

If you had read the accompanying article that was linked in the piece you sited, you would have found the following information which clearly states that only the Verizon 5S or 5C can be used on AT&T:

A1533 GSM (AT&T and T-MOBILE): The GSM version will work on AT&T and T-Mobile. It is distinguished from the Verizon phone in that it does not contain a CDMA radio, which Verizon (and Sprint) have adopted for their voice transmission protocol. The Model A1533 GSM, which is advertised as the AT&T version, will not work for voice calls on Verizon for technical reasons, nor will Verizon let you register the AT&T/T-Mobile phone on its network because it does not have CDMA capabilities. If you purchase one of these phones for use on T-Mobile, the carrier will unlock it after you have been a customer for 40 days. AT&T will also unlock their phones.

The article you site was focused on unlocked handsets, which is why I linked my previous piece on the technology of switching between carriers.

According to Verizon, they do not accept IPhones from TMobile and will only buy those phones back. I was just offered $200 per phone which seemed low to me. I’m not very educated on the issue and based on this article thought that they ought to accept TMobile IPhone 5′s. However, their retort was that they cannot accept the IMEI starting with 010 that TMobile provides. I’ll be Googling to try to find more information and to see if Verizon changed their policy (or if I’m misreading something).

There have been several readers who have commented on this issue, so I will summarize what I wrote in the article and the link within the article: Only the Verizon 5S has the capability to work on Verizon, T-Mobile, and AT&T. No other iPhone 5S can work on the Verizon network because it does not have a CDMA radio. However, a Verizon 5S (or 5C) WILL work on T-Mobile and AT&T because these carriers do not require CDMA for voice transmission. If you buy a Verizon handset, it is unlocked and can be programmed to work on the other two carriers. The converse is not true and Verizon does not recognize the equipment type for the other carriers because the hardware is not compatible. A T-Mobile or AT&T phone can work on each other’s network, but NOT on Verizon.

I have an issue with changing providers between countries. Last year I bought unlocked iPhone 5s. It worked well in USA, but on my return to Poland (and changing sim card) it gives me only one answer: sim card not valid (I tried 3 providers). It required another trip to USA to go to apple store and deal with it. Unfortunately, genius bar was not able to fix it and they just gave a new (probably refurbished?) iPhone 5s, which was giving the same message: sim card not valid (Polish card flew to USA as well). IS there anything that can be done so I am not left with an iPod, instead of iPhone?

“If you are using an Apple iPhone 5c or 5s you can * easily switch your service among three of the four major carriers * in the United States. In my article last week I explained how the new iPhones use a wider range of radio spectrum to operate on either Verizon, AT&T, or T-Mobile. You’re no longer locked into one specific carrier in North America. No longer will your investment in an expensive handset deter you from switching.”

The article goes on to discuss how to handle a 5s being switched to Verizon from another network? Which of the two of the three remaining major carriers would that be if T-mobile, AT&T and Sprint iPhone 5s’ will not work on Verizon?

On that note, the article is completely in contrast with the link to the previous article you noted. In fact, the way this article is written (with specific instructions) not many readers would go out of their way to reference the prior article.

It’s a shame that this article ranks high in the google results on this issue yet is so off the mark that many of us have wasted an inordinate amount of time and experienced great frustration. Please edit this article so no one else finds themselves in the same situation. Not everyone reads the comments.

The best hot-to article I have come across on the topic. Especially the section on updating the iPhone profile that will be helpful for those of us who need to switch to reseller carriers like Straight Talk, etc.